"At Tesco we want to ensure we have the means in place to allow customers to shop whenever, however they want," said Pablo Coberly, engineer at the firm's innovation arm, Tesco Labs.

"We don't envisage Glass becoming the new platform for shopping as its functionality is different, and more immediate. Instead, it compliments other devices and integrates shopping into everyday life because products can be ordered or added as and when customers realise they need replacing.

"We've intentionally kept functionality very basic given the early stages of customer use of Glass. We're keen to see how customers react to shopping with Glassware and welcome feedback or suggestions from customers using Glass."

"We think wearables will be used in more contextual situations, and have developed the app accordingly," said Mike McNamara, head of IT at Tesco.

"For example, if you're at home and see that you've run out of milk, you can use Glass to scan the product barcode and add it to your online grocery basket for home delivery.

"We think it's unlikely that customers will do their entire online grocery shop using wearable tech because it's primarily been designed for 'micro interactions', so we don't think it will replace the smartphone or tablet."

Tesco Grocery is available for free download through the MyGlass app store.